The present invention relates to injectors, a sample separation apparatus, and methods of injecting a fluidic sample.
In liquid chromatography, a fluidic sample and an eluent (liquid mobile phase) may be pumped through conduits and a separation unit such as a column in which separation of sample components takes place. The column may comprise a material which is capable of separating different components of the fluidic sample. The separation unit may be connected to other fluidic members (like a sampler or an injector, a detector) by conduits. Before the fluidic sample is introduced into a separation path between a fluid drive unit (in particular a high pressure pump) and the separation unit, a predefined amount of fluidic sample shall be intaken from a sample source (such as a sample container) via an injection needle into a sample loop by a corresponding movement of a piston within a metering device. This usually occurs in the presence of a significantly smaller pressure than what the separation unit is run with. Thereafter, an injector valve is switched so as to introduce the intaken amount of fluidic sample from the sample loop of a metering path into the separation path between fluid drive unit and the separation unit for subsequent separation.
Injector valves may be configured as rotatable valves having a stator (which may have one or a plurality of fluid ports) and a rotor (which may have a plurality of grooves for connecting respective ones of the fluid ports) being rotatable with regard to the stator to thereby establish a desired fluid communication state between fluid ports and grooves. In order to be capable to withstand high pressure values of for instance up to 1200 bar in a fluid tight manner, it is necessary to press the rotor against the stator.
U.S. Pat. No. 3,940,994 discloses a high pressure sample injector for liquid chromatographs. The apparatus includes a structure defining a cylindrical dispensing chamber for receiving the sample to be injected into the flow path of a high pressure stream of carrier fluid in a liquid chromatograph. Control structure is interposed between the dispensing chamber and the flow path of the carrier stream for preventing liquid flow from the carrier stream to the dispensing chamber, and for enabling flow in the opposite direction only when the pressure in the dispensing chamber at least equals the carrier stream pressure. A pressurizing apparatus is connected to the dispensing chamber to raise its pressure, when desired, to a value at least equal to that of the carrier stream, in order that the sample may be injected into the carrier without reducing the carrier stream pressure.
US 2015/0226710 discloses a method for feeding a sample into an analysis branch of a liquid chromatography system. A solvent or a solvent mixture from at least one solvent branch is supplied as first volume flow into the analysis branch. At least one sample from at least one sample branch is fed as second volume flow into the analysis branch within a predetermined time interval. The volume flow is reduced to an extent during the predetermined time interval, and a third volume flow resulting from the sum of the volume flows remains substantially constant in the analysis branch.
US 2016/0069844 discloses a method and a system for injecting a sample into a flow of a liquid chromatography system. The method includes combining a flow of a sample and a flow of a mobile phase to create a diluted sample in the system flow. The volumetric flow rate of the sample is controlled to be at a value that yields a desired dilution ratio for the diluted sample. The particular value at which the volumetric flow rate is maintained can be determined from the desired value of the dilution ratio and the volumetric flow rate of the mobile phase. System embodiments include a syringe that can be used to provide a sample solution at a controllable volumetric flow rate for combination with a high pressure mobile phase.
However, the functionality of conventional injectors is limited.